Nicole Kidman's role as the face of Etihad Airways has drawn criticism from the Association of Professional Flight Attendants.

The union, which represents 25,000 flight attendants, including nearly 19,000 female crew members, has asked the actress to end her involvement with a company that has been cited for gender discrimination.

APFA sent an open letter to the 47-year-old mother of four, in which association President Laura R. Glading implored Kidman to sever ties with the company.

"We urge you, on behalf of the women and girls that you spoke of so eloquently, not to play a part in promoting Etihad Airways, a company that imposes abusive labor practices on its female employees and whose sole owner is a government that stands against the very world that you imagine," Glading's letter reads.

The letter cited a Wall Street Journal report that said Etihad "may fire women if they become pregnant" and forces flight attendants to live in "confinement" in secure compounds, conditions that the APFA had fought to eliminate "decades ago in the United States."

Kidman has been a staunch supporter for women's rights worldwide since being appointed as a U.N. Women Goodwill Ambassador in January 2006. She was honored in 2013 for her advocacy.

Glading praised her involvement, but pointed out the contradiction.

"Using your profile and stature for such a noble endeavor is commendable," Glading said in the letter. "However, we believe those efforts are at odds with your prominent role in an advertising campaign for Etihad Airways."

Etihad Airways, the second-largest airline of the United Arab Emirates fleet, which employs 24,000 staff, responded to the APFA's claims and requested that Kidman continue her association.

"Our commitment to the welfare, safety, and well-being of the diverse group of men and women who have worked so hard to make Etihad Airways great is one of our airline's top priorities," the company said in a statement.

"When a cabin crew member informs Etihad of a pregnancy, she is provided with appropriate ground duties for the duration of their pregnancy. During this time, she remains fully compensated and fully engaged on the ground."